US20120138529A1 - Method and apparatus for recovering a metal and separating arsenic from an arsenic containing solution - Google Patents

Method and apparatus for recovering a metal and separating arsenic from an arsenic containing solution Download PDF

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US20120138529A1
US20120138529A1 US11/958,644 US95864407A US2012138529A1 US 20120138529 A1 US20120138529 A1 US 20120138529A1 US 95864407 A US95864407 A US 95864407A US 2012138529 A1 US2012138529 A1 US 2012138529A1
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arsenic
solution
containing solution
fixing agent
fixing
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John L. Burba, III
Carl R. Hassler
C. Brock O'Kelley
Charles F. Whitehead
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Molycorp Minerals LLC
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
    • B01J20/0207—Compounds of Sc, Y or Lanthanides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
    • B01J39/08—Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
    • B01J39/10—Oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4676—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction
    • C02F1/4678—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction of metals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/103—Arsenic compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds

Definitions

  • This invention relates generally to the removal of arsenic from arsenic bearing materials, and specifically, to the fixing of arsenic from solutions formed from such materials.
  • arsenic in waters, soils and waste materials may originate from or have been concentrated through geochemical reactions, mining and smelting operations, the land-filling of industrial wastes, the disposal of chemical agents, as well as the past manufacture and use of arsenic-containing pesticides. Because the presence of high levels of arsenic may have carcinogenic and other deleterious effects on living organisms and because humans are primarily exposed to arsenic through drinking water, the U.S. Environmental Protection Agency (EPA) and the World Health Organization have set the maximum contaminant level (MCL) for arsenic in drinking water at 10 parts per billion (ppb).
  • MCL maximum contaminant level
  • Arsenic occurs in the inorganic form in aquatic environments primarily the result of dissolution of solid phase arsenic such as arsenolite (As 2 O 3 ), arsenic anhydride As 2 O 5 ) and realgar (AsS 2 ).
  • Arsenic occurs in water in four oxidation or valence states, i.e., ⁇ 3, 0, +3, and +5. Under normal conditions arsenic is found dissolved in aqueous or aquatic systems in the +3 and +5 oxidation states, usually in the form of arsenite (AsO 2 ⁇ 1 ) and arsenate (AsO 4 ⁇ 3 ).
  • arsenic in which the arsenic exists in the +3 oxidation state, is only partially removed by adsorption and coagulation techniques because its main form, arsenious acid (HAsO 2 ), is a weak acid and remains un-ionized at pH levels between 5 and 8 when adsorption is place most effective.
  • HsO 2 arsenious acid
  • the present invention provides a method for recovering a metal and separating arsenic from an arsenic-containing solution.
  • the method includes the steps of contacting an arsenic-containing solution with a fixing agent under conditions in which at least a portion of the arsenic is fixed by the fixing agent to yield an arsenic-depleted solution and an arsenic-laden fixing agent, the fixing agent comprising a rare earth-containing compound; separating the arsenic-laden fixing agent from the arsenic-depleted solution; and separating a recoverable metal from one or more of the arsenic-containing solution and the arsenic-depleted solution.
  • the rare earth-containing compound can include one or more of cerium, lanthanum, or praseodymium. Where the rare earth-containing compound comprises a cerium-containing compound, the cerium-containing compound can be derived from thermal decomposition of a cerium carbonate. The rare earth-containing compound can include cerium dioxide. When a recoverable metal is in solution in the arsenic-containing solution, the fixing agent comprises an insoluble compound that does not react with the recoverable metal to form an insoluble product.
  • the arsenic-containing solution can be contacted with the fixing agent by flowing the arsenic-containing solution through a bed of the fixing agent or by adding the fixing agent to the arsenic-containing solution.
  • the arsenic-containing solution can have a pH of more than about 7, or more than about 9, or more than about 10, when the arsenic-containing solution is contacted with the fixing agent.
  • the arsenic-containing solution can have a pH of less than about 7, or less than about 4, or less than about 3, when the arsenic-containing solution is contacted with the fixing agent.
  • the arsenic-containing solution can include at least about 1000 ppm inorganic sulfate when the arsenic-containing solution is contacted with the fixing agent.
  • One or more of the arsenic-containing solution and the arsenic-depleted solution can include a recoverable metal.
  • the recoverable metal can include a metal from Group IA, Group IIA, Group VIII and the transition metals. Separating the recoverable metal from the arsenic-containing solution can include electrolyzing or precipitating the recoverable metal from the arsenic-containing solution. Separating the recoverable metal from the arsenic-depleted solution can include electrolyzing or precipitating the recoverable metal from the arsenic-depleted solution.
  • the method can optionally includes the steps of contracting an arsenic-bearing material with a leaching agent to form an arsenic-containing solution and arsenic-depleted solids, and separating the arsenic-depleted solids from the arsenic-containing solution.
  • the leaching agent can include one or more of an inorganic salt, an inorganic acid, an organic acid, and an alkaline agent.
  • the method can optionally include the step of adding the arsenic-depleted solids to a feedstock in a metal refining process to separate the recoverable metal.
  • the present invention provides as apparatus for recovering a metal and separating arsenic from an arsenic-containing solution.
  • the apparatus includes an arsenic fixing unit for receiving an arsenic-containing solution.
  • the arsenic fixing unit includes a contact zone having a fixing agent comprising a rare earth-containing compound for contacting the arsenic-containing solution and fixing at least a portion of the arsenic to yield an arsenic-depleted solution and an arsenic-laden fixing agent.
  • the contact zone of the arsenic fixing unit can be disposed in a tank, pipe, column or other suitable vessel.
  • the fixing agent comprises a rare earth-containing compound.
  • the rare earth-containing compound can include one or more of cerium, lanthanum, or praseodymium. Where the rare earth-containing compound comprises a cerium-containing compound, the cerium-containing compound can be derived from thermal decomposition of a cerium carbonate. The rare earth-containing compound can include cerium dioxide.
  • a separator is provided for separating the arsenic-laden fixing agent from the arsenic-depleted solution.
  • the apparatus includes a metal recovery unit operably connected the arsenic fixing unit for separating a recoverable metal from one or more of the arsenic-containing solution and the arsenic-depleted solution.
  • the metal recovery unit can include one or more of an electrolyzer and a precipitation vessel.
  • the apparatus can optionally further include a second arsenic fixing unit that comprises a contact zone having a fixing agent comprising a rare earth-containing compound for contacting the arsenic-containing solution and fixing at least a portion of the arsenic to yield an arsenic-depleted solution.
  • the apparatus can include a manifold in fluid communication with an inlet of each of the arsenic fixing units for selectively controlling a flow of the arsenic-containing solution to each of the arsenic fixing units, for selectively controlling a flow of a sluce stream to each of the arsenic fixing units and/or for selectively controlling a flow of the fixing agent to each of the arsenic fixing units.
  • the apparatus can optionally include a leaching unit for containing an arsenic-bearing material and contacting the arsenic-bearing material with a leaching agent under conditions such that at least a portion of the arsenic is extracted to form an arsenic-containing solution and arsenic-depleted solids.
  • a separator can be provided to separate the arsenic-containing solution from the arsenic-depleted solids.
  • the apparatus can optionally include a filtration unit connected to the arsenic fixing unit for receiving the arsenic-laden fixing agent and producing a filtrate.
  • the filtration unit can optionally be in fluid communication with an inlet of the arsenic fixing unit for recycling the filtrate to the arsenic fixing unit.
  • FIG. 1 is a flow chart representation of a method of the present invention.
  • FIG. 2A is a schematic view of an apparatus of the present invention.
  • FIG. 2B is a schematic view of an apparatus of the present invention.
  • FIG. 3 is a schematic view of an apparatus of the present invention.
  • FIG. 4 is a schematic view of an apparatus of the present invention.
  • any aqueous solution that contains undesirable amounts of arsenic examples include, among others, well water, surface waters, such as water from lakes, ponds and wetlands, agricultural waters, industrial process streams, wastewater and effluents from industrial processes, and solutions formed from industrial waste and byproducts.
  • Such solutions may be formed by leaching an arsenic-bearing material.
  • materials can include byproducts and waste materials from industries such as mining, metal refining, steel manufacturing, glass manufacturing, chemical and petrochemical, as well as contaminated soils, wastewater sludge, and the like.
  • More specific examples can include mine tailings, mats and residues from industrial processes, soils contaminated by effluents and discharges from such processes, spent catalysts, and sludge from wastewater treatment systems. While portions of the disclosure herein refer to the removal of arsenic from mining tailings and residues from hydrometallurgical operations, such references are illustrative and should not be construed as limiting.
  • the arsenic-containing solution can contain other inorganic contaminants, such as selenium, cadmium, lead, mercury, chromium, nickel, copper and cobalt, and organic contaminants.
  • the disclosed methods can remove arsenic from such solutions even when elevated concentrations of such inorganic contaminants are present. More specifically, arsenic can be effectively removed from solutions comprising more than about 1000 ppm of inorganic sulfates.
  • the arsenic-containing solution can also contain particularly high concentrations of arsenic. Solutions prepared from such materials can contain more than about 20 ppb arsenic and frequently contain in excess of 1000 ppb arsenic. The disclosed methods are effective in decreasing such arsenic levels to amounts less than about 20 ppb, in some cases less than about 10 ppb, in others less than about 5 ppb and in still others less than about 2 ppb.
  • the disclosed methods are also able to effectively fix arsenic from solution over a wide range of pH levels, as well as at extreme pH values.
  • this capability eliminates the need to alter and/or maintain the pH of the solution within a narrow range when removing arsenic.
  • it adds flexibility in that the selection of materials and processes for leaching arsenic from an arsenic-bearing material can be made without significant concern for the pH of the resulting arsenic-containing solution.
  • elimination of the need to adjust and maintain pH while fixing arsenic from an arsenic-containing solution provides significant cost advantages.
  • a method for recovering a metal and separating arsenic from an arsenic-containing solution.
  • the method includes the steps of contacting an arsenic-containing solution with a fixing agent under conditions in which at least a portion of the arsenic is fixed by the fixing agent to yield an arsenic-depleted solution and an arsenic-laden fixing agent, the fixing agent comprising a rare earth-containing compound; separating the arsenic-laden fixing agent from the arsenic-depleted solution; and separating a recoverable metal from one or more of the arsenic-containing solution and the arsenic-depleted solution.
  • the arsenic-containing solution is contacted with the fixing agent in a tank, container or other vessel suitable for holding such solutions and materials.
  • the solution is at a temperature and pressure, usually ambient conditions, such that the solution remains in the liquid state. Elevated temperature and pressure conditions may be used.
  • the tank may optionally include a mixer or other means for promoting agitation and contact between the arsenic-containing solution and fixing agent.
  • suitable vessels are described in U.S. Pat. No. 6,383,395, which description is incorporated herein by reference.
  • the fixing agent can be any rare earth-containing compound that is effective at fixing arsenic in solution through precipitation, adsorption, ion exchange or other mechanism.
  • the fixing agent can be soluble, slightly soluble or insoluble in the aqueous solution.
  • the fixing agent has a relatively high surface area of at least about 70 m 3 /g, and in some cases more than about 80 m 3 /g, and in still other cases more than 90 m 3 /g.
  • the fixing agent can be substantially free of arsenic prior to contacting the arsenic-containing solution or can be partially-saturated with arsenic. When partially-saturated, the fixing agent can comprise between about 0.1 mg and about 80 mg of arsenic per gram of fixing agent.
  • the fixing agent can include one or more of the rear earths including lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium erbium, thulium, ytterbium and lutetium.
  • specific examples of such materials that have been described as being capable of removing arsenic from aqueous solutions include trivalent lanthanum compounds (U.S. Pat. No. 4,046,687), soluble lanthanide metal salts (U.S. Pat. No. 4,566,975), lanthanum oxide (U.S. Pat. No.
  • lanthanum chloride U.S. Pat. No. 6,197,201
  • mixtures of lanthanum oxide and one or more other rare earth oxides U.S. Pat. No. 6,800,204
  • cerium oxides U.S. Pat. No. 6,862,825
  • mesoporous molecular sieves impregnated with lanthanum U.S. Patent Application Publication No. 20040050795
  • polyacrylonitrile impregnated with lanthanide or other rare earth metals U.S. Patent Application Publication No. 20050051492.
  • rare earth-containing fixing agents may be obtained from any source known to those skilled in the art.
  • the rare-earth containing compound can comprise one or more of cerium, lanthanum, or praseodymium.
  • the fixing agent comprises a compound containing cerium
  • the fixing agent can be derived from cerium carbonate. More specifically, such a fixing agent can be prepared by thermally decomposing a cerium carbonate or cerium oxalate in a furnace in the presence of air.
  • the fixing agent comprises cerium dioxide
  • Water-soluble cerium compounds such as ceric ammonium nitrate, ceric ammonium sulfate, ceric sulfate, and ceric nitrate can also be used as the fixing agent, particularly where the concentration of arsenic in solution is high.
  • the rare earth-containing fixing agents of the present invention are particularly advantageous in their ability to remove arsenic from solution over a wide range of pH values and at extreme pH values.
  • the pH of the arsenic-containing solution can be less than about 7 when the arsenic-containing solution is contacted with the first portion of fixing agent. More specifically, the pH of the arsenic-containing solution can be less than about 4, and still more specifically, the pH of the arsenic-containing solution can be less than about 3 when the arsenic-containing solution is contacted with the first portion of fixing agent. In other embodiments, the pH of the arsenic-containing solution can be more than about 7 when the arsenic-containing solution is contacted with the first portion of fixing agent. More specifically, the pH of the arsenic-containing solution can be more than about 9, and still more specifically, the pH of the arsenic-containing solution can be more than about 10 when the arsenic-containing solution is contacted with the first portion of fixing agent.
  • Acid addition can include the addition of a mineral acid such as hydrochloric or sulfuric acid.
  • Alkaline addition can include the addition of sodium hydroxide, sodium carbonate, calcium hydroxide, ammonium hydroxide and the like.
  • the fixing agent is preferably an insoluble compound that selectively adsorbs arsenic from the solution and does not react or reacts only weakly with the recoverable metal to form an insoluble product.
  • a fixing agent that does not contain a rare earth compound can also be used.
  • Such optional fixing agents can include any solid, liquid or gel that is effective at fixing arsenic in solution through precipitation, adsorption, ion exchange or some other mechanism. These optional fixing agents can be soluble, slightly soluble or insoluble in the aqueous solution.
  • Optional fixing agents can include particulate solids that contain cations in the +3 oxidation state that react with the arsenate in solution to form insoluble arsenate compounds.
  • Such solids include alumina, gamma-alumina, activated alumina, acidified alumina such as alumina treated with hydrochloric acid, metal oxides containing labile anions such as aluminum oxychloride, crystalline alumino-silicates such as zeolites, amorphous silica-alumina, ion exchange resins, clays such as montmorillonite, ferric salts, porous ceramics.
  • Optional fixing agents can also include calcium salts such as calcium chloride, calcium hydroxide, and calcium carbonate, and iron salts such as ferric salts, ferrous salts, or a combination thereof.
  • iron-based salts include chlorides, sulfates, nitrates, acetates, carbonates, iodides, ammonium sulfates, ammonium chlorides, hydroxides, oxides, fluorides, bromides, and perchlorates.
  • a source of hydroxyl ions may also be required to promote the co-precipitation of the iron salt and arsenic.
  • optional fixing agents are known in the art and may be used in combination with the rare earth-containing fixing agents described herein. Further, it should be understood that such optional fixing agents may be obtained from any source known to those skilled in the art.
  • the arsenic-laden fixing agent is separated from an arsenic-depleted solution in a separator.
  • One or more steps may be required to separate the solution from such liquids solids.
  • a variety of options are available, including screening, settling, filtration, and centrifuging, depending on the size and physical characteristics of the solids.
  • Particulate solids such as insoluble fixing agents and insoluble arsenic-containing compounds can be separated from the various solutions described herein for further processing.
  • Any liquid-solids separation technique such as screening, filtration, gravity settling, centrifuging, hydrocycloning or the like can be used to remove such particulate solids.
  • An optional flocculant, coagulant or thickener can also be added to the solution before the particulate solids are removed.
  • Such agents are useful for achieving a desired particle size and improving the settling properties of the arsenic-laden fixing agent.
  • inorganic coagulants include ferric sulfate, ferric chloride, ferrous sulfate, aluminum sulfate, sodium aluminate, polyaluminum chloride, aluminum trichloride among others.
  • Organic polymeric coagulants and flocculants can also be used, such as polyacrylamides (cationic, nonionic, and anionic), EPI-DMA's (epichlorohydrin-dimethylamines), DADMAC's (polydiallydimethyl-ammonium chlorides), dicyandiamide/formaldehyde polymers, dicyandiamide/amine polymers, natural guar, etc.
  • the arsenic laden fixing agent can optionally be directed to a filtration unit that is connected to the separator wherein the fixing agent is filtered to produce a filtrate and arsenic-laden solids.
  • the solids are directed out of the filtration unit for appropriate disposal or further handling.
  • the filtration unit has an outlet in fluid communication with the arsenic fixing unit for recycling the filtrate to the contract zone where it is combined with in-coming fresh arsenic-containing solution and contacted with fixing agent.
  • the methods of the present invention include the step of separating a recoverable metal from one or more of the arsenic-containing solution and the arsenic-depleted solution.
  • recoverable metal can include virtually any metal of interest, but specifically includes metals from Group IA, Group IIA, Group VIII, and the transition metals.
  • the recoverable metal can be separated from an arsenic-containing solution and/or an arsenic-depleted solution by a variety of methods.
  • the solution can be combined with a process stream or added to the feedstock in a metal refining process, such as one utilizing electrochemical methods.
  • a metal refining process such as one utilizing electrochemical methods.
  • Electrowinning or electrorefining are widely used processes for recovering and refining copper, nickel, zinc, lead, cobalt, and manganese dioxide.
  • Another method for separating a recoverable metal from the arsenic-containing solution includes precipitating the recoverable metal from the solution.
  • Precipitation reactions are widely used to recover metal values or to remove impurities from process streams and waste waters.
  • Many hydrometallurgical processes contain one or more precipitation steps. For instance, hydroxide is used to precipitate iron from acid streams, neutralize acid streams for disposal, recover nickel and cobalt hydroxide from sulfate liquors, and remove metals from wastewater. Platinum group metals are also recovered from acidic leach solutions by precipitation. Sulfide is another common compound used in precipitation steps. Hydrogen sulfide is used to recover copper from copper-bearing streams and nickel and cobalt from acid sulfate liquors.
  • an apparatus of the invention can optionally include a precipitation vessel.
  • a separator as described herein can optionally be used to separate precipitated metals from the arsenic-containing solution.
  • the arsenic-containing solution is optionally prepared by leaching the arsenic from an arsenic-bearing material.
  • the arsenic-bearing material is contacted with an arsenic leaching agent to form an arsenic-containing solution and arsenic-depleted solids.
  • Arsenic can be leached from solids such as contaminated soils, industrial byproducts and waste materials by leaching or extraction to release the arsenic from such solids.
  • leaching refers to the dissolution of metals or other compounds of interest from an ore or other solid into an appropriate solution.
  • pretreatment or processing such as by grinding or milling, may be desired to promote dissolution and release of arsenic.
  • the arsenic leaching agent can include one or more of an inorganic salt, an inorganic acid, an organic acid and an alkaline agent.
  • the selection of the leaching agent will depend on the nature of the arsenic-bearing material and other compounds that are present.
  • Specific examples of inorganic salt leaching agents include potassium salts such as potassium phosphate, potassium chloride, potassium nitrate, potassium sulfate, sodium perchlorate and the like.
  • examples of inorganic acids that may be used to leach arsenic from solids include sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, perchloric acid and mixtures thereof.
  • Organic acid leaching agents can include citric acid, acetic acids and the like.
  • Alkaline agents can include sodium hydroxide among others.
  • arsenic leaching agents and their use may be had by reference to M. Jang et al., “Remediation Of Arsenic-Contaminated Solids And Washing Effluents”, Chemosphere, 60, pp 344-354, (2005); M. G. M. Alam et al., “Chemical Extraction of Arsenic from Contaminated Soil”, J. Environ Sci Health A Tox Hazard Subst Environ Eng., 41 (4), pp 631-643 (2006); and S. R. Al-Abed et al., “Arsenic Release From Iron Rich Mineral Processing Waste; Influence of pH and Redox Potential”, Chemosphere, 66, pp 775-782 (2007).
  • the arsenic-containing solution is separated from insoluble materials, referred to herein as arsenic-depleted solids.
  • One or more steps may be required to separate the solution from such liquids solids.
  • a variety of options are available, including screening, settling, filtration, and centrifuging, depending on the size and physical characteristics of the solids.
  • the present invention provides as apparatus for recovering a metal and separating arsenic from an arsenic-containing solution.
  • the apparatus includes an arsenic fixing unit for receiving an arsenic-containing solution.
  • the arsenic fixing unit includes a contact zone having a fixing agent comprising a rare earth-containing compound for contacting the arsenic-containing solution and fixing at least a portion of the arsenic to yield an arsenic-depleted solution and an arsenic-laden fixing agent.
  • the contact zone of the arsenic fixing unit can be disposed in a tank, pipe, column or other suitable vessel.
  • the fixing agent comprises a rare earth-containing compound.
  • the rare earth-containing compound can include one or more of cerium, lanthanum, or praseodymium. Where the rare earth-containing compound comprises a cerium-containing compound, the cerium-containing compound can be derived from thermal decomposition of a cerium carbonate. The rare earth-containing compound can include cerium dioxide.
  • a separator is provided for separating the arsenic-laden fixing agent from the arsenic-depleted solution.
  • the apparatus includes a metal recovery unit operably connected the arsenic fixing unit for separating a recoverable metal from one or more of the arsenic-containing solution and the arsenic-depleted solution.
  • the metal recovery unit can include one or more of an electrolyzer and a precipitation vessel.
  • the apparatus can optionally further include a second arsenic fixing unit that comprises a contact zone having a fixing agent comprising a rare earth-containing compound for contacting the arsenic-containing solution and fixing at least a portion of the arsenic to yield an arsenic-depleted solution.
  • the apparatus can include a manifold in fluid communication with an inlet of each of the arsenic fixing units for selectively controlling a flow of the arsenic-containing solution to each of the arsenic fixing units, for selectively controlling a flow of a sluce stream to each of the arsenic fixing units and/or for selectively controlling a flow of the fixing agent to each of the arsenic fixing units.
  • the apparatus can optionally include a leaching unit for contacting the arsenic-bearing material with a leaching agent under conditions such that at least a portion of the arsenic is extracted to form an arsenic-containing solution and arsenic-depleted solids.
  • a separator can be provided to separate the arsenic-containing solution from the arsenic-depleted solids.
  • the apparatus can optionally include a filtration unit connected to the arsenic fixing unit for receiving the arsenic-laden fixing agent and producing a filtrate.
  • the filtration unit can optionally be in fluid communication with an inlet of the arsenic fixing unit for recycling the filtrate to the arsenic fixing unit.
  • FIG. 1 is a flow chart representation of method 100 .
  • Method 100 includes step 115 of arsenic-containing solution is contacted with fixing agent under conditions in which at least a portion of the arsenic is fixed by the fixing agent to yield an arsenic-depleted solution and an arsenic-laden fixing agent, the fixing agent comprises a rare earth-containing compound.
  • the arsenic-laden fixing agent is separated from the arsenic-depleted solution.
  • a recoverable metal is separated from one or more of the arsenic-containing solution or the arsenic-depleted solution.
  • FIG. 2A is a schematic view of apparatus 200 A.
  • Apparatus 200 A includes optional leaching unit 205 A for preparing an arsenic-containing solution from arsenic-bearing material 201 A.
  • Arsenic-depleted solids can optionally be conveyed on line 230 A to metal recovery unit 235 A.
  • the arsenic-containing solution is directed to fixing unit 280 A, which has contact zone 215 A.
  • the fixing agent in contact zone 215 A fixes and removes arsenic from the solution to yield an arsenic-depleted solution.
  • Separator 220 A separates the arsenic-depleted solution from the arsenic-laden fixing agent.
  • the arsenic depleted solution is directed to metal recovery unit 235 A through line 225 A.
  • FIG. 2B is a schematic view of apparatus 200 B.
  • Apparatus 200 B includes optional leaching unit 205 B for preparing an arsenic-containing solution from arsenic-bearing material 201 B.
  • the arsenic-containing solution is directed to precipitation vessel 235 B where a recoverable metal is precipitated from the arsenic-containing solution.
  • the arsenic-containing solution is separated from the precipitated metals by separator 231 B and directed to fixing unit 280 B through line 214 B.
  • Fixing unit 280 B has contact zone 215 B.
  • the fixing agent in contact zone 215 B fixes and removes arsenic from the solution to yield an arsenic-depleted solution.
  • Separator 220 B separates the arsenic-depleted solution from the arsenic-laden fixing agent, which is directed out of the fixing unit through line 225 B.
  • FIG. 3 is a schematic view of apparatus 300 that includes arsenic fixing units 380 A and 380 B and filtration unit 340 .
  • the apparatus 300 includes manifold 360 and a plurality of columns 370 A and 370 B. The columns have contact zones 315 A and 315 B and separators 320 A and 320 B, respectively.
  • Manifold 360 receives arsenic-containing solution through line 314 , a sluce solution through line 312 and fresh fixing agent through line 313 .
  • Manifold 360 selectively controls the flow of each of these materials to columns 370 A and 370 B through lines 362 A and 362 B respectively.
  • Valves (not shown) at the bottom of each of columns 370 A and 370 B control the flow of arsenic-depleted solution or arsenic-laden fixing agent from the columns.
  • manifold 360 interrupts the flow of arsenic-containing solution to column 370 A.
  • the valve (not shown) at the bottom of column 370 A is actuated to allow the arsenic-laden fixing agent to flow out through line 321 to filtration unit 340 .
  • Manifold 360 directs a sluce stream or solution into column 370 A to wash residual fixing agent from the column.
  • the slurried fixing agent is likewise directed to filtration unit 340 where a filtrate and arsenic-laden solids are produced.
  • the filtrate is directed back to manifold 360 through line 341 where it is combined with fresh arsenic-containing solution entering the manifold.
  • the arsenic-laden solids are conveyed out of filtration unit 340 on line 343 for disposal or handling.
  • the valve is at the bottom of column 370 A is closed and manifold 360 directs a flow of fresh fixing agent into contact zone 315 A. While this operation is underway, manifold 360 maintains the flow of arsenic-containing solution into column 370 B so as to achieve a continuous process for removing arsenic from the solution.
  • the arsenic-depleted solution separated from the fixing agent in column 370 B is then directed out through line 325 for further processing or disposal.
  • FIG. 4 illustrates apparatus 400 that includes tank 415 , separator 420 , filtration unit 440 and metal recovery unit 435 .
  • An arsenic-containing solution is directed into tank 415 containing a fixing agent.
  • the fixing agent produces an arsenic-depleted solution and an arsenic-laden fixing agent that are directed through line 417 to separator 220 .
  • the arsenic-laden fixing agent settles to the bottom and the arsenic-depleted solution is directed through an overflow outlet into line 425 and directed to metal recovery unit 435 .
  • the arsenic laden fixing agent is directed through line 421 to a filtration unit where a filtrate and arsenic-laden solids are produced.
  • the solids are directed out of the filtration unit through line 443 and the filtrate is recycled to an inlet of tank 415 .
  • the metal recovery unit produces an arsenic-containing solution
  • that solution can be directed to an inlet of tank 415 though line 450 .

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  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Hydrology & Water Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Removal Of Specific Substances (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
US11/958,644 2006-12-28 2007-12-18 Method and apparatus for recovering a metal and separating arsenic from an arsenic containing solution Abandoned US20120138529A1 (en)

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US9975787B2 (en) 2014-03-07 2018-05-22 Secure Natural Resources Llc Removal of arsenic from aqueous streams with cerium (IV) oxide compositions
CN108218090A (zh) * 2018-03-23 2018-06-29 美丽国土（北京）生态环境工程技术研究院有限公司 浸出液处理装置、重金属淋洗设备及浸出液处理方法
CN111729389A (zh) * 2020-07-09 2020-10-02 辽宁莱特莱德环境工程有限公司 一种无机盐的精制处理系统
US20200331780A1 (en) * 2016-05-11 2020-10-22 Pentair Filtration Solutions, Llc Water ionization system and method
CN112973178A (zh) * 2021-02-26 2021-06-18 重庆文理学院 一种中药制药用压榨萃取装置

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US9885095B2 (en) 2014-01-31 2018-02-06 Goldcorp Inc. Process for separation of at least one metal sulfide from a mixed sulfide ore or concentrate
US10370739B2 (en) 2014-01-31 2019-08-06 Goldcorp, Inc. Stabilization process for an arsenic solution
US11124857B2 (en) 2014-01-31 2021-09-21 Goldcorp Inc. Process for separation of antimony and arsenic from a leach solution
US9975787B2 (en) 2014-03-07 2018-05-22 Secure Natural Resources Llc Removal of arsenic from aqueous streams with cerium (IV) oxide compositions
US10577259B2 (en) 2014-03-07 2020-03-03 Secure Natural Resources Llc Removal of arsenic from aqueous streams with cerium (IV) oxide compositions
US20200331780A1 (en) * 2016-05-11 2020-10-22 Pentair Filtration Solutions, Llc Water ionization system and method
CN108218090A (zh) * 2018-03-23 2018-06-29 美丽国土（北京）生态环境工程技术研究院有限公司 浸出液处理装置、重金属淋洗设备及浸出液处理方法
CN111729389A (zh) * 2020-07-09 2020-10-02 辽宁莱特莱德环境工程有限公司 一种无机盐的精制处理系统
CN112973178A (zh) * 2021-02-26 2021-06-18 重庆文理学院 一种中药制药用压榨萃取装置

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CA2674088A1 (en) 2008-07-10
EP2114569A1 (en) 2009-11-11
EA200970644A1 (ru) 2010-12-30
EP2114569A4 (en) 2010-12-29
AP2597A (en) 2013-02-18
CL2007003858A1 (es) 2009-03-06
ECSP099543A (es) 2009-10-30
BRPI0719615A2 (pt) 2015-06-16
MX2009006973A (es) 2009-10-14
AU2007340045A1 (en) 2008-07-10
WO2008082959A1 (en) 2008-07-10
AP2009004923A0 (en) 2009-08-31
CO6231011A2 (es) 2010-12-20
CN101636229A (zh) 2010-01-27

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